Obstructive sleep apnoea involves repeated partial or complete collapse of the upper airway during sleep, causing breathing to stop for periods and the sleeper to briefly rouse to resume it — often dozens of times an hour, without any memory of it.
Population estimates suggest it affects a substantial proportion of adults, with a large majority undiagnosed. That combination — common, consequential, treatable, unrecognised — makes it worth understanding.
Why it goes unnoticed
The person experiencing it is asleep. The arousals are too brief to be remembered, so they have no direct awareness of anything happening.
What they experience is the downstream effect: waking unrefreshed, daytime sleepiness, difficulty concentrating, morning headaches, irritability. All of which get attributed to stress, ageing, workload, or simply not getting enough sleep.
Meanwhile the observable signs — loud snoring, witnessed pauses in breathing, gasping — are only visible to somebody else. People who sleep alone frequently have no information at all.
Snoring is also so common and so socially normalised that it's treated as an irritation rather than a symptom.
Why it matters
The consequences extend well beyond feeling tired.
Each apnoeic event causes a drop in blood oxygen and a surge in sympathetic nervous system activity. Repeated hundreds of times a night, over years, this is associated with a range of outcomes.
Hypertension, particularly hypertension resistant to treatment, has a well-established association. There are also associations with cardiovascular events, atrial fibrillation, stroke and impaired glucose metabolism.
The relationship is complicated by shared risk factors — obesity is a risk factor for both apnoea and cardiovascular disease — and the association persists after adjustment in many studies.
The most immediately dangerous consequence is daytime sleepiness and its effect on driving. Studies of drivers with untreated apnoea have found elevated collision risk, and treatment reduces it.
Who's at risk
Several factors increase likelihood.
Excess weight, particularly around the neck, is the strongest modifiable risk factor. Male sex, with the gap narrowing after menopause. Increasing age. Anatomical factors — a narrow airway, large tonsils, certain jaw configurations. Family history. Alcohol before sleeping, which relaxes airway muscles.
An important point that's frequently missed: apnoea occurs in people who are not overweight. Anatomical predisposition alone is sufficient, and slim people with symptoms are sometimes dismissed on the assumption that it isn't relevant to them.
It's also underdiagnosed in women, partly because presentation can differ — with fatigue, insomnia and mood symptoms more prominent than classic loud snoring — and partly because clinical suspicion has historically been lower.
Getting assessed
Diagnosis requires a sleep study, and the pathway varies by health system.
Home sleep testing has become widely available and is adequate for many cases — a device worn overnight measuring airflow, oxygen saturation and effort.
Laboratory polysomnography is more comprehensive, measuring sleep stages as well, and is used where the picture is complex or other sleep disorders are suspected.
Screening questionnaires exist and are used to identify who should be tested. They're reasonably sensitive and not diagnostic on their own.
If you snore loudly, have been observed to stop breathing, wake unrefreshed, or experience daytime sleepiness that doesn't resolve with adequate sleep opportunity, that's worth raising with a doctor rather than assuming it's normal.
Treatment
Continuous positive airway pressure is the standard treatment for moderate to severe cases. A machine delivers pressurised air through a mask, holding the airway open.
It's highly effective when used. Adherence is the main problem — a significant proportion of people struggle with the mask, and long-term use rates are lower than they should be.
Most adherence problems are solvable with mask fitting adjustments, humidification, or pressure setting changes. Anyone who tried it and abandoned it years ago should know that equipment has improved considerably and that persistence with support usually resolves the issues.
Mandibular advancement devices, custom-made dental appliances that hold the jaw forward, are an option for milder cases and for people who cannot tolerate pressure therapy.
Positional therapy, where apnoea occurs predominantly when sleeping on the back.
Weight loss, where relevant, can substantially reduce severity and in some cases resolve mild cases.
Surgical options exist for specific anatomical causes and are generally considered where other approaches have failed.
Why raising it is worth it
The reason to pursue this is that the treatment effect is unusually direct.
People who are treated effectively frequently describe the change in fairly dramatic terms — waking rested for the first time in years, daytime sleepiness resolving, cognitive fog lifting.
That's not universal and the improvement in symptoms is substantially more consistent than in most chronic conditions.
Given how many people have it without knowing, and how ordinary the symptoms seem, it's one of the more worthwhile things to mention to a doctor if any of this sounds familiar.
General information only. If you suspect sleep apnoea, seek assessment from a qualified healthcare professional.
Children too
Worth a separate note because presentation differs and it is missed even more frequently. Obstructive sleep apnoea occurs in children, commonly related to enlarged tonsils and adenoids.
The daytime picture is often not sleepiness but the opposite — hyperactivity, inattention and behavioural difficulties, which can be mistaken for attention disorders. Bedwetting, mouth breathing and poor growth are other signals.
Treatment, frequently surgical removal of tonsils and adenoids where indicated, resolves it in a large proportion of cases with substantial improvement in the daytime symptoms. If a child snores loudly most nights and has behavioural or attention difficulties, it is worth raising specifically.